The invention relates to a dishwasher, particularly a domestic dishwasher, that has a container hood made at least partly of metal and includes a container casing, consisting of two side walls and a container roof, and also a rear wall, as well as a rinsing tub, not belonging to the container hood and made of plastic, as the base of a treatment container for accommodating items to be rinsed, with said container having a filling opening that can be closed by means of a door.
The treatment container of dishwashers is usually made of a special high-grade stainless steel. The treatment container comprises at least two constituent parts. What is termed the container casing embodies the side walls and roof of a container hood of the treatment container. A separately embodied rear wall is a constituent part of the container hood and is joined to the container casing in a liquid-tight manner by welding. The container hood's constituent parts are for reasons of corrosion resistance made of a high-grade chromium-nickel steel, which is relatively expensive. Chromium-nickel steel is used because, for example, the rear wall is joined to the container casing by welding. Using chromium-nickel steel ensures corrosion resistance at the weld seams also.
For cost reasons it would be advantageous if major constituent parts of the container hood could be made from a more ordinary and economical chromium steel because production costs can then be reduced. The problem with joining chromium steel to chromium-nickel steel by welding is that what is termed crevice corrosion can occur in a dishwasher in the region of the join.
For that reason recourse is made, as already described in the introduction, to using more expensive chromium-nickel steel since corrosion may otherwise occur in regions continually wetted with liquid or moisture, for example at sections that are welded together and in seal receptacles.
A typical structure of a conventional dishwasher is described in U.S. Pat. No. 6,045,203. The dishwasher therein disclosed has a bent container casing which on its filling opening is provided with a flange embodying a front area and having rounded upper corners. To make it easier to integrate the dishwasher into a built-in kitchen, corner members are detachably fitted onto the upper corners to produce square upper corners. The corners as well as trim members fitted on the edges are each made of a plastic material and are fitted on the container hood's flange. The corner members themselves are secured to the trim members. Highly corrosion-resistant materials are employed in producing the dishwasher described in the US publication, with expensive stainless steel being preferred. Only little deformation stability, for example during transportation, is provided owing to embodying the container casing, consisting of the side walls and container roof, as a single piece.
A household appliance having a treatment container exhibiting greater stability than the dishwasher described above is known from DE 44 43 920 C2. For installing or securing side walls, in particular if an insulation (for example noise and/or thermal insulation) is to be provided between the treatment container and side walls, said household appliance has a frame serving also to install the appliance and make it rigid. To make it easily possible to separate the parts made of different materials, the German (DE) patent specification provides for releasably joining at least one frame part to the treatment container in a form-fit manner. To ensure stability at the same time, frame parts on opposite sides of the treatment container are releasably mutually joined around the treatment container in a form-fit manner and braced. A frame part consists therein of U-shaped profile rods, with preferably two frames being arranged fitted over the treatment container, one adjacent to its filling opening and one adjacent to its rear side, with the free ends of the frame limbs pointing downwards. Whereas the rinsing container is to be made of a special stainless steel, the frame parts can be made of a plastic material. The front U-frame forms the edging of a filling opening of the rinsing container. The U-frame is for that purpose made of profile rods substantially rectangular in cross-section and has a rectangular projection that is accommodated in recesses in the rinsing container. The U-frames furthermore have receptacles for side walls of a machine-housing trim, for an insulating mat, and for a seal.
DE 25 43 822 and DE 24 20 302 disclose dishwashers each having modules made of metal and of plastic. Said modules are in both cases joined to each other using a seal. Plastic is therein in each case used for making the dishwashers' rinsing tubs. The consideration underlying that approach is that the costs of producing the domestic appliances can be reduced by extensively replacing with plastic those metal components requiring to be made of an expensive special stainless steel for reasons of corrosion resistance.